State Machine based control system for booklet maker.

Challenge

An established print and mail handling company was looking to expand its
product line into the print-on-demand document marketplace. The new products required
a high degree of modularity to support various material form factors, as well as
printing and feeding platforms. In addition, the products would be creating customer
specific documents of variable size and content, requiring high-speed reading of
coded information on each sheet. These features required a rapidly configurable
control system capable of handling and tracking material from multiple, simultaneous
input channels.

Solution and Results

The team created a modular controls framework using UML state machines to implement
the core behaviors for each of the various reading, feeding, collating, merging,
stitching, and delivery devices. The framework was designed such that new modules
and system configurations could be created by simply defining them in configuration
files, rather than having to write new code.

The controls framework handled tracking the material, along with its data, as it
was processed through the machine, allowing for variable collations based on unique
data for each sheet. The tracking system also allowed for integrity checks to be
performed based on the encoded information. Such checks included account number
consistency, as well as proper sequence and number of pages. In the event of integrity
or other errors, the system was able to auto-recover by re-synchronizing the collations.

The high throughput requirements were met by the control system's ability to arbitrate
material delivery between modules. The arbitration system optimized time between
deliveries, and allowed for addition time between sheets and packets at the end
of collations. Additional features supporting high throughput included an adaptive
learning algorithm to optimize feeder speeds and sensing material arrival and departure
times.